The invention relates to the post fluorination of synthetic resin articles of manufacture, e.g., containers.
Fluorine, owing to its aggressive nature, is a hazardous working substance which attacks, corrodes, or even destroys a great variety of materials. In particular, it is very toxic to the human organism.
For this reason, special measures have to be taken when using fluorine in industrial processes so as to ensure the safety of such a facility and the occupants therein. For example, special conduit systems, seals and encapsulations of entire facilities are required. Even delivery and storage must undergo special precautions.
At the present time, fluorine is available for industrial use, especially for fluorination processes, in gas bottles in a mixture with nitrogen. The fluorine concentration of such gaseous mixture is low for safety reasons, merely about 10-20%. Inasmuch as in the fluorination of synthetic resin articles, fluorine concentrations of only about 10% or less are sufficient, the fluorine-nitrogen supply gas is generally further diluted with pure nitrogen to the extent desired.
Two fluorination methods are known, in principle, in the production of fluorinated synthetic resin articles, especially hollow components: fluorination is performed either in one operating step (inline process) with the molding of the article, for example during blow molding (e.g., German Patent No. 2,401,948), or the fluorination is conducted in a separate working step (offline process) subsequent to the actual manufacturing procedure (German Patent No. 2,644,508).
However, in either case, when performing the fluorination, care must be taken to handle the fluorine-containing gaseous mixture safely. This array of problems is also dealt with in the inline procedure discussed in German Patent No. 3,523,137.